Move the various seq_ functions, as well as std::(stable_)sort,
std::accumulate, std::transform, std::find, std::find_if to their C++20
std::ranges counterparts.
With the ~--eval~ option you can evaluate an expression in mu/scm
environment. For example:
$ mu scm --eval \
'(format #t "found ~d match(es)\n" (length (mfind "hello")))'
found 7173 match(es)
Add command-line parameter and implement.
Add a method personal? to check if some string looks like a personal address;
add docs / tests as well.
Rename the all-labels method into simply 'labels'
Make some define* into define-method, for consistency.
Implement accessing the MIME-parts + docs + test.
Implement saving attachments to file.
Implement creating messages from files.
Refactor / rename functions to be more uniform.
Implement support for "header" and "body" procedures, with require loading the
message file from disk, and create a foreign object for the message.
We keep those alive in a vector, and hook up a finalizer.
Update docs & tests as well.
This implements the new scm/guile bindings for mu, to replace the deprecated
guile/ (at some point in the future).
For now, we allow for creating a guile shell with mu support.
